The V-band luminosity function of galaxies in A2151

¹ Instituto de Astrofísica de Canarias, Calle Vía Láctea s/n, 38205 La Laguna, Tenerife, Spain e-mail: [ruben;cmt;jalfonso]@iac.es
² Laboratoire d'Astrophysique de Marseille, BP 8, Traverse du Siphon, 13376 Marseille, France e-mail: jorge.iglesias@oamp.fr
³ Instituto de Astrofísica de Andalucía, CSIC, Apdo. 3004, 18080 Granada, Spain e-mail: jvm@iaa.es


Received: 5 August 2004
Accepted: 17 December 2004

Abstract

We present a wide field V-band imaging survey of approximately 1 deg² (~ Mpc²) in the direction of the nearby cluster of galaxies Abell 2151 (the Hercules Cluster). The data are used to construct the luminosity function (LF) down to , thus allowing us to study the dwarf galaxy population in A2151 for the first time. The obtained global LF is well described by a Schechter function with best-fit parameters and . The radial dependence of the LF was investigated, with the faint-end slope tending to be slightly steeper in the outermost regions and farther away than the virial radius. Given the presence of significant substructure within the cluster, we also analysed the LFs in three different regions. We find that the dwarf to giant ratio increases from the northern to the southern subcluster, and from low to high local density environments, although these variations are marginally significant (less than 2σ).